How do I handle a custom field that is an object instead of a simple string?

They're constantly adding custom fields to JIRA where I work. One of the latest requires a full object rather than a simple string, as the data. It represents a drop-down field with fixed selections.

Here's what the JSON looks like:
```json
"customfield_17100": {
"disabled": false,
"id": "15700",
"self": "https://someserver.com/rest/api/2/customFieldOption/15700",
"value": "Some text value"
},
```
Setting a regular customfield doesn't work, since it only allows strings for the values, not objects. If the JSON is pass _as_ a string, it doesn't count as a object.